The present invention relates generally to intravascular stents for implanting into a living body. In particular, the present invention relates to intravascular stents that are expanded by an inflatable balloon catheter and to a method and apparatus for mounting and securing a stent on a balloon catheter.
Intravascular stents having a constricted diameter for delivery through a blood vessel and an expanded diameter for applying a radially outwardly extending force for supporting the blood vessel are known in the art. Selfexpandable articulated stents are described, for example, in U.S. Pat. No. 5,104,404, entitled xe2x80x9cArticulated Stentxe2x80x9d to Wolff. Balloon expandable articulated stents are commercially available under the trade name Palmaz-Schatz Balloon-Expandable stents from Johnson and Johnson International Systems Co.
In conventional stent mounting and securing procedures, the stent is usually first slid over the distal end of a balloon catheter so that the expandable balloon is disposed within the longitudinal bore of the stent. The stent is then crimped or pinched to mount or secure the stent and maintain its position with respect to the expandable balloon as the balloon catheter is advanced to the target area. This crimping is often done utilizing the fingers or a plier-like device to pinch the stent. One shortcoming of this conventional mounting and securing means is that it often produces irregular distortion of the stent which could cause trauma to the lumen being treated. Another shortcoming is that it may weaken a portion or portions of the stent which could result in stent failure. Yet another shortcoming of conventional mounting and securing methods is that they may distort the stent in such a way as to cause the stent to expand in the target area in a non-uniform manner which could result in a portion of the lumen not being properly supported.
Yet another shortcoming of conventional mounting and securing methods is irregular distortion of the stent could produce protrusions in the stent which could cause trauma to the patient.
Therefore, it would be highly desirable to have a method and an apparatus that permits a stent to be secured over the expandable balloon of a balloon catheter without causing irregular distortion or weakening the stent.
It is an object of this invention to provide an apparatus for securing a stent on a balloon catheter by substantially uniformly distorting the stent.
It is another object of this invention to provide an apparatus for securing a stent on a balloon catheter that reduces the likelihood that the stent will expand in a nonuniform manner.
It is yet another object of this invention to provide a method of securing a stent on a balloon catheter that reduces the likelihood that the stent will be weakened by the securing procedure.
It is a further object of this invention to provide an apparatus for securing a stent on a balloon catheter, comprising:
a) a first clamping portion provided with a first clamping portion recess, said first clamping portion recess sized and adapted to receive a stent crimping sleeve;
b) a second clamping portion provided with a second clamping portion recess, said second clamping portion recess sized and adapted to receive a stent crimping sleeve, said first clamping portion recess and said second clamping portion recess defining a longitudinal stent crimping sleeve channel having a variable cross-sectional diameter, said first and said second clamping portions adapted for movement in a first direction away from each other to a first position and in a second direction toward each other to a second position to selectively impart pressure to a stent crimping sleeve disposed in said longitudinal stent crimping sleeve channel, said clamping portion recesses sized and adapted so that said longitudinal stent crimping sleeve channel has a substantially circular cross-sectional diameter when said first and said second clamping portions are in said second position;
c) a stent crimping sleeve disposed in said crimping sleeve channel, said sleeve having a first end, a second end, an outer surface, and an inner surface defining a longitudinal stent crimping bore therethrough, said longitudinal stent crimping bore having a selectively variable-substantially circular cross-sectional diameter and sized and adapted to receive a balloon catheter with a stent mounted thereon, said stent crimping sleeve further adapted to selectively and substantially uniformly vary said substantially circular cross-sectional diameter of said longitudinal stent crimping bore in response to pressure applied to said external surface of said stent crimping sleeve by said first clamping portion and said second clamping portion when said first clamping portion and said second clamping portion are moved in said second direction.
It is still another object of this invention to provide a method of securing an expandable stent having a longitudinal bore on a balloon catheter, comprising the steps of:
a) constructing an apparatus comprising: a first clamping portion provided with a first clamping portion recess, said first clamping portion recess sized and adapted to receive a stent crimping sleeve; a second clamping portion provided with a second clamping portion recess, said second clamping portion recess sized and adapted to receive a stent crimping sleeve, said first clamping portion recess and said second clamping portion recess defining a longitudinal stent crimping sleeve channel having a variable cross-sectional diameter, said first and said second clamping portions adapted for movement in a first direction away from each other to a first position and in a second direction toward each other to a second position to selectively impart pressure to a stent crimping sleeve disposed in said longitudinal stent crimping sleeve channel, said clamping portion recesses sized and adapted so that said longitudinal stent crimping sleeve channel has a substantially circular cross-sectional diameter when said first and said second clamping portions are in said second position; a stent crimping sleeve having a first end, a second end, an outer surface, and an inner surface defining a longitudinal stent crimping bore therethrough having a selectively variable substantially circular cross-sectional diameter and sized and adapted to receive a balloon catheter with a stent mounted thereon, said stent crimping sleeve further adapted to selectively and substantially uniformly vary said substantially circular cross-sectional diameter of said longitudinal stent crimping bore in response to pressure applied to said external surface of said stent crimping sleeve by said first clamping portion and said second clamping portion;
b) disposing said stent crimping sleeve in said stent crimping sleeve channel;
c) disposing said stent in said longitudinal stent crimping bore of said stent crimping sleeve;
d) disposing said balloon catheter in said longitudinal bore of said stent; and
e) moving said first and said second stent clamping portions from said first position to said second position so as to apply pressure to said external surface of said stent crimping sleeve in an amount sufficient to decrease the substantially circular cross-sectional diameter of said longitudinal stent crimping bore in an amount sufficient for said inner surface of said stent crimping sleeve to impart sufficient pressure to said stent to secure said stent to said balloon catheter.
It is a further object of this invention to provide an apparatus for securing a stent on a balloon catheter, comprising:
a) a first clamping portion having a first clamping portion recess and a second clamping portion having a second clamping portion recess, said first and said second clamping portion recesses defining a longitudinal stent crimping element channel with a variable cross-sectional diameter, said first and said second clamping portions adapted for movement in a first direction away from each other to a first position and in a second direction toward each other to a second position;
b) a plurality of crimping elements disposed within said longitudinal stent crimping element channel defining a stent crimping sleeve channel having a variable cross-sectional diameter, said plurality of crimping elements adapted for movement in a first direction away from each other to a first position and in a second direction toward each other to a second position; and
c) a stent crimping sleeve disposed in said longitudinal stent crimping sleeve channel, having a first end, a second end, an outer wall, and an inner wall defining a longitudinal bore therethrough having a selectively variable substantially circular cross-sectional diameter, said clamping portions said crimping elements, and said sleeve adapted and disposed so that when said first clamping portion, said second clamping portion, and said plurality of crimping elements are disposed in the second position, said crimping elements define a longitudinal stent crimping sleeve channel having a substantially circular crosssectional diameter and said longitudinal stent crimping bore defines a longitudinal bore having a substantially circular cross-sectional diameter.
It is a yet another object of this invention to provide an apparatus for securing a stent on a balloon catheter, comprising:
a) a first clamping portion and a second clamping portion, said first clamping portion provided with a first surface, a second surface and a third surface defining a first clamping portion recess, said second clamping portion provided with a first surface, a second surface, a third surface, a fourth surface and a fifth surface defining a second clamping portion recess, said first and said second clamping portion recesses defining a longitudinal stent crimping element channel with a variable diameter, said first and said second clamping portions adapted for movement in a first direction away from each other to a first position and in a second direction toward each other to a second position;
b) a first crimping element disposed within said longitudinal stent crimping element channel said first crimping element provided with a first crimping element contact surface, a second crimping element contact surface, a first clamping portion contact surface, and a stent crimping sleeve contact surface;
c) a second crimping element disposed within said longitudinal stent crimping channel, said second crimping element provided with a first crimping element contact surface, a second crimping element contact surface, a first clamping portion contact surface, and a stent crimping sleeve contact surface;
d) a third crimping element disposed within said longitudinal stent crimping channel, said third crimping element provided with a first crimping element contact surface, a second crimping element contact surface, a second clamping portion contact surface, and a stent crimping sleeve contact surface;
e) a fourth crimping element disposed within said longitudinal stent crimping channel, said fourth crimping element provided with a first crimping element contact surface, a second crimping element contact surface, a second clamping portion contact surface, and a stent crimping sleeve contact surface, said crimping elements adapted for movement in a first direction away from each other to a first position and in a second direction towards each other to a second position, said stent crimping sleeve contact surfaces defining a stent crimping sleeve channel having a variable cross-sectional diameter that is substantially circularxe2x80x94when said plurality of crimping elements are disposed in said second position; and
f) a stent crimping sleeve disposed in said longitudinal stent crimping sleeve channel, said sleeve having a first end, a second end, an outer wall, and an inner wall defining a longitudinal bore therethrough having a selectively variable substantially circular crosssectional diameter, said clamping portions, said crimping elements, and said sleeve adapted and disposed so that when said first clamping portion and said second clamping portion are in the second position, said crimping sleeve contact surfaces define a stent crimping sleeve channel having a substantially circular cross-sectional diameter and said longitudinal bore defines a longitudinal bore having a substantially circular cross-sectional diameter.